Christopher Chabri and Daniel Simons surprise the world with their classic experiment where people are asked to count the number of passes people in white dress make during a basketball drill video. Halfway through the video a Gorilla appears in the video, beats his chest and walks out of the frame. When asked if people noticed anything strange during the video 50% of people fail to notice the gorilla completely. The book builds on the theory that while our brains are powerful they are nowhere nearly as attentive as we think they are. The book focuses on ways in which illusions deceive our brains and how each one of us have our own versions of what we see.